The Shop by Brand page allows the user to see all the brands in your store, choose a brand, and see the products for the Brand.  The Shop by Brand link is not included in the navigation out-of-box, you can add it using the URL/Brand/List

To prepare the brand list, you need to add brands and set them up, see 

Adding a Brand and Managing Brands

The following features are available on this page:

• See a list of Brands.
• Click on a letter to quickly navigate to brands starting with that letter.
• Select a brand to see the search results page for that brand.
• Advertisement Banners - defined in Store Experience